The Fifth Element #84

Were it my place to hand out awards for "The Most Forthright People in Audio," Michael Grace of Grace Design would be at the top of the list. Years ago, after I'd given stellar recommendations of Grace's 901 and m902 headphone-amplifier-DAC-line-stage models, I asked Grace if I could audition his full-rack–size, more fully featured m904 Stereo Monitor Controller. He told me that he didn't think that was necessary, because the m904's sound was extremely similar to the sound of the smaller m902—it just had a different feature set, and he believed that the additional features were not things that Stereophile readers were likely to need. That is the only case I can recall of a manufacturer's declining an offer of additional coverage in Stereophile.

Fast forward to 2013. Taking a gander at his company's website, I think it fair to say that Michael Grace has become a fan of DSD downloads. He writes: "DSD sounds stunningly natural. . . . If you're the type to seek out this kind of fidelity, we can't recommend it enough." This was on the page devoted to the m904's replacement, the m905 ($3495), which supports DSD 128x (5.6448MHz) via the DoP v.1.1 protocol (DSD packed into PCM frames)—via not only its USB input, but also its S/PDIF and AES/EBU (balanced digital) inputs. Perhaps because I've worn out and retired "Gloriosky!," all I could say was "Woober Joobers!"

Still, out of an abundance of caution, I must emphasize that the m905 handles PCM only up to 192kHz; at present, the m905 can't handle DXD at 352.8kHz, or 384kHz program material (such as that available for download from Norwegian record label 2L). Grace Design claims that, as with the m903, and basic visual design aside, the m905 is, compared to its predecessor, close to a clean-sheet-of-paper redesign in which particular attention has been paid to the analog circuitry and to Grace's proprietary phase-locked loop (PLL) reclocking scheme. Therefore, when I asked Grace if I could listen to his smaller product's larger sibling, unlike last time, he fairly bubbled over with enthusiasm. He assured me that even his design team had been unprepared for how much better than the m904 the m905 sounded.

The Grace M905
The m905 is unlike any other consumer-audio component now offered. It took a little getting used to, but it quickly became very addictive. The differences begin with the m905's form factor. The m905's is a rack-mountable component two rack units (3.5") high and 17" wide. Its front panel is empty, except for a headphone jack, an illuminated power button, their silk-screened icons, and the names of the product and its manufacturer.


On the m905's rear panel are, by my count, 33 connectors and switches. These include balanced and single-ended analog inputs (the m905 handles analog signals entirely in that domain), six digital inputs, two digital outputs, Word Clock throughput, Talkback circuit In/Out, three sets of Monitor analog outputs, Cue analog outputs, and Multipurpose analog outputs. Michael Grace states that the proprietary, high-precision S•Lock PLL digital-clock regeneration used in the m905 is a significant improvement over that used in the m903. The m905's USB connection is the preferred asynchronous type.

Except for the power switch, all of the m905's controls are found on a remote control about the size of an iPad mini (8.9" wide by 2.2" high by 5.1" deep) but thicker and heavier. For a variety of good and sufficient reasons, the remote is connected to the mainframe with a multi-conductor cable with 15-pin D-sub connectors at either end (these have nonstandard pin assignments). The stock cable is 25' long because, in a recording or mastering studio, the mainframe will often be bolted into an equipment rack some distance from the mastering position. Grace will provide a shorter cable at no additional charge if the request is made at the time of the original order. They're also exploring the practical possibility of controlling the m905 via an iPhone/iPad app. The remote comes with a detachable base, from which the control panel can be tilted up about 30°.

The remote's front panel is dominated by, on the right, a large, finely machined volume knob and multifunction switch, and on the left by a color graphical LCD display (not a touchscreen) with adjustable brightness. The screen's image is divided into left and right halves, each of which has a prominent volume-setting readout: for the selected monitor speakers (left) and the headphone outputs (right). Smaller readouts cover such system information as the selected monitors, whether or not a subwoofer is engaged, and the digital input signal's sampling rate, bit depth, and lock status.


For me, the most fascinating readout on the LCD screen was the real-time display of sound-pressure level at the mastering position, courtesy a microphone built into the remote (!). The particulars of SPL metering can be selected via the Setup menu, including canceling the SPL display. Note that the remote displays SPL, not loudness. Professional loudness meters cost as much as or more than the entire m905.

If you have separate control and tracking rooms, the same microphone that feeds the SPL display can be used for Talkback. Even if you don't, it can be fun to hold down the large Talkback button (to the right of the Volume knob), watch it light up red, and tell Ella what a fine job she's just done.

Grace Design claims that the remote's design replicates the solid feel of traditional hardware, while adding the greater information and functionality of a graphical user interface. I applaud them for putting all of the m905's important functions under mechanical control. I think that a first-class rotary volume control is far more intuitive and precise, and more likely to hold up under heavy use, than a piece of glass you slide your fingertip over. And the remote and its base have a textured, fingerprint-resistant silver finish that fairly shouts Authentic German Engineering—even though the m905 and all Grace products are designed and built in Lyons, Colorado (footnote 1).

The m905's remote offers three forms of mechanical control. The speed-sensitive volume knob toggles at a tap between controlling (in 0.5dB steps) the monitor speakers selected and the two headphone jacks (one on the mainframe, one at the rear edge of the remote). Eight small, black buttons, four each above and below the LCD screen, select the active input. Illuminated pushbuttons on either side of and above the volume knob select among three possible monitor-speaker outputs; enable frequently used control functions such as solo, subwoofer control, sum-to-mono; and diminish the output by 20dB or mute it entirely.

All of that might seem daunting; even more daunting is the very complete owner's manual. However, setting up and getting sound out of the m905 was not difficult at all. The remote's cable connects to the mainframe's rear panel. Connect a digital source (in my case, Parasound's excellent Halo CD 1) and connect balanced cables to the mainframe's analog outputs. Those balanced cables connect to your amplifier, with adapters if need be. Grace provides a sturdy power cord. Press the power button on the mainframe's front panel; it should softly glow a comforting light green.

As part of its "Please allow us to make your life as foolproof as possible" mission statement, every time the m905 is powered up, it resets the volume controls for both the monitor speakers and the headphones to "0." Yay! That'll prevent some "whoopsie" moments, especially if the previous night's work got a little loud. And so you don't have to crank the volume control all the way up to a usable level every time, in the Setup menu you can arrange it so that when you hold down the volume control, the output level moves to your predetermined level (in my case, 70dB).

After setup, all you have to do is select a source and rotate the volume knob (or press and hold, if you've entered a default level) until you get sound. The silky-smooth feel of the volume knob and its silky-smooth detented action strike me as more of those little touches that indicate that Michael Grace was strongly influenced by the time he spent at the Jeff Rowland Design Group. Grace's products not only represent exceptional value for money; they also manage to make a lot of workaday professional components look like mud fences.

The m905, as described above, is pretty much plug'n'play right out of the box. However, what I've described is the simplest, plainest-vanilla setup. There is a wealth of options for customizing setup and use. The two that will likely make the biggest differences for audiophiles are the abilities to rename the input-selection buttons' legends on the LCD display and to individually adjust the inputs' levels.

Features that home audiophiles aren't likely ever to need include eight channels of optical ADAT ins and outs (if you don't know what ADAT is, you absolutely don't have to worry about it), and up to 10 channels of computer audio via USB. Those are for the serious home-studio musician, or a professional with a digital audio workstation (DAW) program such as Pro Tools.

While the m905 lacks a physical balance control, the balance can be adjusted on each loudspeaker pair's Setup screen. There is no polarity-invert function, owing to the added complication of implementing that for headphones. However, signal polarity can often be inverted at the digital source, or in DAW software. Like the m903, the m905 offers selectable headphone cross-feed.

There's not space here to get as deeply as I might wish into the m905's inner workings. Suffice it to say that the m905 is based on cutting-edge technology, seamlessly implemented. Its DAC chip is a Burr-Brown PCM1798 whose interpolation filter 8x-oversamples an S/PDIF input from a "Red Book" source. (Sample rates higher than "Red Book"'s 44.1kHz are oversampled 4x or 2x.) The delta/sigma modulator then converts the 352.8kHz PCM signal to what Michael Grace believes is a 6-bit/2.88MHz signal. (Texas Instruments' current data sheet for the PCM1798 does not specify bit depth.)

Footnote 1: Grace Design, PO Box 1812, Lyons, CO 80540. 4689 Ute Highway, Lyons, CO 80503. Tel: (303) 823-8100. Web:
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stereoGoodness's picture

It's all fine and good to see a column on the m905, but I'm waiting for a full review of the m920, which is more affordable and probably more useful to the average audiophile.

John Marks's picture

The m920 was only announced within the past 45 days or so, and seeing as Sweetwater Sound and one other e-tailer do not yet show it or tease it, I have no idea whether it is really in the pipeline in terms of a retailer's being able to ship within a week or two. It doesn't look it. And Stereophile does not review prototypes or pre-release products. We have to review a serially-numbered real product, one just like real customers are buying.

I am sorry to disappoint you, but, I don't see myself as obtaining a m920. There are too many great new products out there, and I can't devote column space to variations on a theme from the same company, especially when I have reviewed so many iterations of the m901 already.

If the price of the m905 is prohibitive for you, that is that. You can decide whether you wish to order an m920 from a retailer or etailer that offers a money-back guarantee, and see if it fits your needs.

I tend to disagree with your assessment of the m920; I think that the average audiophile will fall in love with its unusual feature set, including real-time SPL readout.


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